<template>
  <!-- 商品分类导航 -->
  <!-- 全局组件，放入components -->
  <div class="type-nav">
    <div class="container">
      <div @mouseleave="leaveIndex" @mouseenter="enterShow">
        <!--        事件委派，加上一层div-->
        <h2 class="all">全部商品分类</h2>
        <transition name="sort">
          <div class="sort" v-show="show">
            <div class="all-sort-list2" @click="goSearch">
              <!--            委派-->
              <div class="item" v-for="(c1,index) in categoryList" :key="c1.categoryId">
                <!--              一级分类-->
                <h3 @mouseenter="changeIndex(index)" :class="{cur:currentIndex===index}">
                  <a href="javascript:void(0)" :data-category-name="c1.categoryName" :data-category1-id="c1.categoryId">{{
                      c1.categoryName
                    }}</a>
                </h3>
                <div class="item-list clearfix" :style="{display:currentIndex===index?'block':'none'}">
                  <!--                二级分类-->
                  <div class="subitem" v-for="c2 in c1.categoryChild" :key="c2.categoryId">
                    <dl class="fore">
                      <dt>
                        <a href="javascript:void(0)" :data-category-name="c2.categoryName"
                           :data-category2-id="c2.categoryId">{{
                            c2.categoryName
                          }}</a>
                      </dt>
                      <dd>
                        <em v-for="c3 in c2.categoryChild" :key="c3.categoryId">
                          <a href="javascript:void(0)" :data-category-name="c3.categoryName"
                             :data-category3-id="c3.categoryId">{{
                              c3.categoryName
                            }}</a>
                        </em>
                      </dd>
                    </dl>
                  </div>
                </div>
              </div>
            </div>
          </div>
        </transition>
      </div>
      <nav class="nav">
        <a href="###">服装城</a>
        <a href="###">美妆馆</a>
        <a href="###">贝贝商城超市</a>
        <a href="###">全球购</a>
        <a href="###">闪购</a>
        <a href="###">团购</a>
        <a href="###">有趣</a>
        <a href="###">秒杀</a>
      </nav>
    </div>
    <br/>
    <br/>
  </div>
</template>

<script>
import {mapState} from 'vuex'
// import _ from 'lodash' //此种引用方式是将其所有函数引入进来
import {throttle} from "lodash";

export default {
  name: "TypeNav",
  computed: {
    ...mapState('home', ['categoryList']), //也可以为函数形式，函数形式的话，函数会被执行一次
  },
  mounted() {
    //如果不是home路由，则将列表隐藏
    this.show = this.$route.name === 'home';
  },
  data() {
    return {
      //存储鼠标指向的一级分类index
      currentIndex: -1,
      show: true
    }
  },
  methods: {
    // changeIndex(currentIndex) {
    //   //改变currentIndex，以实现背景变换
    //   this.currentIndex = currentIndex
    // }
    //加上节流
    changeIndex: throttle(function (currentIndex) {
      this.currentIndex = currentIndex
    }, 50),
    leaveIndex: throttle(function () {
      this.currentIndex = -1
      if (this.$route.name !== 'home') {
        this.show = false
      }
    }, 50),
    goSearch(event) {
      //利用事件委派和函数式导航
      let {categoryName, category1Id, category2Id, category3Id} = event.target.dataset
      if (categoryName) {
        let location = {
          name: 'search'
        }
        let query = {
          categoryName,
        }
        if (category1Id) {
          query.category1Id = category1Id
        } else if (category2Id) {
          query.category2Id = category2Id
        } else if (category3Id) {
          query.category3Id = category3Id
        } else {
          console.log('出错！')
        }
        location.query = query
        //如果有params参数，则带上
        if (this.$route.params) {
          location.params = this.$route.params
        }
        this.$router.push(location)
      }
    },
    enterShow() {
      //当鼠标移入时，让列表显示
      this.show = true
    }
  },
}
</script>

<style scoped lang="less">
.type-nav {
  border-bottom: 2px solid #e1251b;

  .container {
    width: 1200px;
    margin: 0 auto;
    display: flex;
    position: relative;

    .all {
      width: 210px;
      height: 45px;
      background-color: #e1251b;
      line-height: 45px;
      text-align: center;
      color: #fff;
      font-size: 14px;
      font-weight: bold;
    }

    .nav {
      a {
        height: 45px;
        margin: 0 22px;
        line-height: 45px;
        font-size: 16px;
        color: #333;
      }
    }

    .sort {
      position: absolute;
      left: 0;
      top: 45px;
      width: 210px;
      height: 461px;
      position: absolute;
      background: #fafafa;
      z-index: 999;

      .all-sort-list2 {
        .item {
          h3 {
            line-height: 30px;
            font-size: 14px;
            font-weight: 400;
            overflow: hidden;
            padding: 0 20px;
            margin: 0;

            a {
              color: #333;
            }
          }

          .item-list {
            display: none;
            position: absolute;
            width: 734px;
            min-height: 460px;
            background: #f7f7f7;
            left: 210px;
            border: 1px solid #ddd;
            top: 0;
            z-index: 9999 !important;

            .subitem {
              float: left;
              width: 650px;
              padding: 0 4px 0 8px;

              dl {
                border-top: 1px solid #eee;
                padding: 6px 0;
                overflow: hidden;
                zoom: 1;

                &.fore {
                  border-top: 0;
                }

                dt {
                  float: left;
                  width: 54px;
                  line-height: 22px;
                  text-align: right;
                  padding: 3px 6px 0 0;
                  font-weight: 700;
                }

                dd {
                  float: left;
                  width: 415px;
                  padding: 3px 0 0;
                  overflow: hidden;

                  em {
                    float: left;
                    height: 14px;
                    line-height: 14px;
                    padding: 0 8px;
                    margin-top: 5px;
                    border-left: 1px solid #ccc;
                  }
                }
              }
            }
          }
        }

        .cur {
          background-color: skyblue;
        }
      }
    }

    .sort-enter {
      //过渡动画进入的开始阶段
      height: 0px;
    }

    .sort-enter-to {
      //过渡动画进入的结束始阶段
      height: 461px;
    }

    .sort-enter-active {
      transition: all 0.5s;
    }
  }
}
</style>